I had a similar situation with a credit card company years ago - I sent them a check, they didn't actually attempt to cash it until months later. Since I didn't maintain accurate balances on my accounts back then, and just used current balances according to the bank, when they finally did attempt to cash it, it would have over drawn my account and thus was rejected.
The credit card company still wanted their money, and I couldn't tell them "well, as soon as I sell the stuff that I bought on the card, you'll get your money". I owed them, plain and simple. I don't get a grace period with unlimited time until I find someone willing to buy whatever I have.
BTW, there is no legal expiration date on a personal check. Most banks follow the Uniform Commercial Code, and won't cash a stale check, with stale meaning 6 months. In Russ's case, that would mean 9 months after getting the check.
Regardless of all that, if the guy didn't have the money to pay what he owed Russ, he should give the top back, period. Given what's transpired here, my money says that Russ won't even get any money even after selling the car (assuming of course it does actually sell), and he'll likely get some lame ass story like "gee, all the sales proceeds were seized by the court, and I didn't have any control over it".